The present invention related to a preconditioned air unit supplying preconditioned air, i.e. heated air or cooled air, to an aircraft parked on the ground.
On the ground, an aircraft typically uses the auxiliary power unit engine (APU) to drive air-conditioning equipment to cool or heat the aircraft cabin to a temperature that is comfortable for passengers. However, operation of the APU has a high cost in terms of jet fuel consumption, generated acoustic noise, CO.sub.2 emissions, etc. For example, the APU of an A320 aircraft consumes app. 160 l fuel per hour. In addition to the general air pollution, the consumption of one liter of jet fuel leads to emission of 2.5 kg CO.sub.2 into the atmosphere and thus, the APU emits app. 400 kg CO.sub.2 per operational hour.
In order to avoid running the APU on the ground, preconditioned air units have been provided for supplying the required preconditioned air to the parked aircraft. The preconditioned air units are powered from the mains supply made available at the airport in question.
Cost, efficiency, flexibility, and serviceability remain an issue in known preconditioned air units.